From Christopher Hitchens’ biography Hitch 22, remarks he made when he became a U.S. citizen:

For a writer to become an American is to subscribe of his own free will to a set of ideas and principles and to the documents that embody them in written form, all the while delightedly appreciating that the documents can and often must be revised, so that the words therefore constitute, so to say, a work in progress.

Hear, hear. One of the primary elements of the story of America is the gradual extension of those original principles where those who stated them dared not go.